cell membranes and transport Flashcards
what are the two main components on cell membranes
phospholipids and protein
what are phospholipids chemically
glycerol bonded to two fatty acids and a phosphate group
properties of the head and tail of the phospholipids
the head is hydrophilic (phosphate group)
the tail is hydrophobic (fatty acids)
what happens to phospholipids if isolated in water
they form the monolayer which hydrophilic heads in water and tails sticking out into air
how are phospholipids arranged in a cell
phospholipids arranged themselves into a bilayer
why are phospholipids arranged in a bilayer in the cell
as cytoplasm is watery, the tails point towards each other
what is an intrinsic protein
intrinsic proteins span the membrane from one side to the other
what is an extrinsic protein
extrinsic proteins are found in one side of the bilayer or on the surface of the bilayer
what is a channel
some intrinsic proteins that went through the membrane forming a channel
where would the R group (primary sequence) location be if a part of the protein is hydrophilic
hydrophilic parts with the polar/charged R groups are located around the phospholipid heads or on the outside
where would the R group (primary sequence) location part of the protein be if the protein is hydrophobic
hydrophobic portions with non-polar R groups are arranged near/between hydrophobic tails
why are cell membranes selectively permeable
this is because the hydrophobic layer in the middle of the bilayer is impermeable to polar and charged particles. non polar molecules dissolve in the hydrophobic layer and can cross the membrane by simple diffusion
what do channel proteins have lining the space down the middle of the protein
hydrophilic R groups
how do channel proteins work?
these channels are specific to a particular charged or polar particles and allow them to diffuse across the membrane in facilitated diffusion.
what are protein carriers?
some proteins are involved in active transport and facilitated diffusion across the membrane; these are specific to the polar or charged molecules carried
